A resolution emerging from the recent International Whaling Commission (IWC) meeting has given a faint ray of hope to the vaquita, the world's smallest porpoise and an animal on the brink of extinction.

Vaquitas, the estimated 59 that remain, live in the Gulf of California. Since first being listed as critically endangered in 1996, the animal's numbers have dropped precipitously, from a count of 567 in 1997.

The drop is due largely to illegal fishing of the critically endangered totoaba, a fish whose swim bladders are supposed in China to have medicinal value, creating a lucrative black market for the organs. Fishermen employ gill nets - thin lines that are hard for fish to see - to catch the totoaba, but the netting also ensnares vaquitas as bycatch.

The resolution, submitted by 21 countries, including the United States, urges Mexico to toughen its enforcement of illegal fishing and to make permanent a ban on gill nets throughout the vaquita's range.

In 2015, Mexico instituted a two-year ban on gill nets, which expires in May 2017, and increased the vaquita's protected area, but the measures have not proved effective enough.

"Only a permanent, complete, and effective gill net ban in all fisheries operating in the Upper Gulf of California will prevent the imminent extinction of the vaquita," the resolution stated.